Find the coordinate of the fourth vertex of a rectangle with three vertices at (-7, 5), (3, -1), and (-7, -1)

lets say A(-7,5) B(-7,-1) C(3,-1) D(x,y)
u see that x(A )=x( B) and the distance of A and B is 6 units
so x(C)=x(D)=3 and y(D)=5 so that the distance between C and D can be 6 as well
|dw:1348425807971:dw| sorry slow conn :/